Rotary drum filter



Aug. 25, 1936. F. W. YOUNG ROTARY DRUM FILTER Filed lJune 25, 1934 IN V EN TOR.

A TTORNEYS.

Patented Aug. '25, 1936 *UNITED VSTATE ,osant g This invention relates to rotary drum filters, vand in particular to the construction of the and valve of such filters. i Continuous rotary drum lters as at present constructed consist of a drum, the outer surface 'of which is provided with individual compartments. `Each of these compartments communicates with an automatic valve carried on one end of the trunnion by means of suitable piping. lBy 1o means of this automatic valve each of the compartments may be successively subjected tosubatmospheric or atmospheric pressure as desired. for the purpose of forming a cake on the surface of the drum and then discharging it.

li5 One of the objections to the iilters now on the market is that the restriction to the dow of liquid inthe pipes, Ts and elbows connecting the filter compartments `with the automatic valve materially decreases the capacity of the fllter. Fur- 2@ thermore, when the'drum is provided with closed heads or ends, the buoyancy of the drum requires extra heavy construction to take care of the stresses and strains set up by these unbalanced conditions.

M 'in general the object of this invention is to provide a continuous rotary drum lter in which I the network of piping within .the drum is elimlnated.

More specidcally the object of the invention is I 30 the provision o! a drum for continuous filters, the

outer surface of which is provided with inde pendent compartments, eachV communicating by means of ports with the interior of the drum, and

each port having associated with it a valve in the 35 form ofa counterbalanced gravity operated shoe suspended adjacent each of said ports.

A furtherobject of the invention is the provision of a drum having closed ends in which the iti-ate within the is substantially at the so same level as the pulp within the tank in which the drum rotates to thereby eliminate any buoyant eect of the y Y The invention possesses other advantageous features, some oi which with the foregoing, will as be set forth in the following description where that form of the invention which has been selected for illustration inthe drawing accompanying and forming a part oi? the present spec/lrication is outlined in iuii. in said drawing, one 50 torni of the invention is shown, but it is to be understood that it is not ted to such form, since the invention as set iorth. in the claims may be embodied in a plurality o! forms.

Vliteferring to the drawing: 65 Figure 1 is a side elevation partly in section of a rotary drum filter in which the objects of the invention are embodied.

Figure 2 ls a section taken on the line 2-2 of Fig. 1.

Figure 3 is an enlarged perspective View' of one 5 of the counterbalanced gravity operated valves used within the filter drum.

In accordance with the invention, a drum l,. provided with closed heads 2 and 3, is rotatively disposed within a tank t by means of trunnions 5 10 and t, journaled in bearings 'l and t. The trunnion 5 is hollow as clearly shown in Figure 1 and serves toestablish communication between the interior of drum l and a suitable vacuum pump (not shown) for subjecting the interior of the drum and its contents to sub-atmospheric pressure. The trunnion 6 is closed by means of a plate t, and has'associated with it a gear train il which in turn is driven by means of a motor it carried by a suitable bracket formed on one end of the tank, and the bearing t.

The outer surface of the drum l is provided with independent filtrate compartments it, defined by the usual division strips it. Disposed over the division strips it is a supporting screen 25 it which in turn is covered by any suitable nlter `medium it. A port il' is formed in the door of each compartment for the purpose of establishing communication between the' interior of each compartment and the interior of the drum i. Communication between the compartments i3 and the interior of the drum is controlled by means of a counterbalanced gravity operated valve as clearly shown in Figure 3, and'which consists of a fitting it provided at one end with a flange it and at its opposite end with brackets 2Iin which are formed bearings 22. Journaled in the bearings 22 is a shaft 23, to the central portion of which is secured an arcuate shoe or gate 2t, and tothe outer ends of which are se- 40 cured counterweights 25. The radius of curvature of the arcuate shoe 2t is made complementary to the radius of curvature of the free ends 2t of the fitting it so that upon the relative rotation of the shoe 2t and the fitting it these mem- 45 bers will just clear each other. Under' actualoperating conditions the entire valve mechanism is wetted by the filtrate contained within thejdrum i, and therefore although there is some clearance between the shoe 2t and the tting i8 the 50 shoe 2t under these conditions eectively closes the free open end or port of the tting I8. As shown in Figure 2 the fittings i8 are secured to the inner face of the drum l in registration with the port il by means oi the danse I9. It the 56 drum I is of relatively small diameter yor if the compartments i3 are relatively narrow, it is preferable to stagger the ports Il as shown in Figure 1.

By adjusting the relative angular position oi.' the shoe 24 and the counterweights 25 (which may be done by suitable setscrews carried by the hubs of the counterweights the shoe 24 may be made to close the open ends oi' their associated ttings I8 during any particular point of the revolution of the drum i. ure 2 the valves in this instance are closed only on the upper side of the drum during the discharge period of the cycle. Theitrant Within the tank 4 is carried at a level indicated by the line 21 and since the cake forming period should commence as soon as any given compartment is submerged within the filtrant, the valve associated with this compartment should be open Aor begin to open at this point, and should remain open during the entire cake forming period and during the cake drying period so that cake formation and drying may be effected under the inuence of sub-atmospheric pressure. The counterweights 25 should of course be heavy enough to prevent any appreciable rotation of the shoe 24.

It will be noted that by the construction above disclosed the usual automatic valve carried on the end of the drum trunnion has been eliminated, and likewise all oi' the piping, elbows and Ts which have previously been required to establish communication between the ltrate compartments and the valve. In so doing the restriction to the flow of ltrate through the pipes vhas also been eliminated, and consequently a filter of very high capacity has been provided. Furthermore since the ends of the drum are closed and since the level of the filtrate within the drum is substantially the same as the level of the filtrant within the tank, the drum has substantially no buoyant effect, and therefore it is not necessary to provide an extra heavy construction.

I claim:

1. A drum for continuous filters provided on its outer surface with independent filtrate compartments; each filtrate compartment being provided with a. port communicating with the interior of the drum and with a gravity operated valve pivoted about an axis parallel with the axis of the drum and adapted to successively open and close said ports upon the rotation of the drum.

2. A drum for continuous filters provided on its outer surface with independent ltrate compartments each compartment having a port communicating with the interior of the drum and a As shown in Figcounterbalanced gravity operated shoe pivoted adjacent said drum about yan axis parallel with the axis of the drum, and in line with said ports so that each port is closed by its associated shoe once during each rotation of the drum.

3. A drum for continuous filters provided on its outer surface with independent filtrate compartments, each compartment having a port formed. in its oor communicating with the lnterior: of said drum, the centers of said ports lying in a lcommon plane; and a gravity operated shoe pivoted adjacent said ports about an axis parallel with the axis of the drum, and with its center lying in said common plane so that said ports are closed once during each rotation of the drum.

4. A drum for continuous lters provided on its outer surface with independent ltrate compartments, each compartment being provided with a port communicating with the interior of the drum; a gravity operated counterbalanced shoe pivoted adjacent each of said ports about an axis parallel within the axis of the drum and adapted to close its associated port upon relative motion therewith.

5. A filter comprising a closed ended drum provided with independent filtrate compartments and rotatably mounted within a tank; a port in each compartment communicating with the interior of the drum; sleeve ttings secured to the interior of said drum adjacent saidy ports and tatably secured to said sleeves and arranged in one position to register with and close the outer ends thereof; and counter weights associated With-said shoes for maintaining them in a predetermined position.

'7. In a rotary drum filter provided with independent ltrate compartments each having a port communicating with the interior of the drum; sleeves secured over said ports; pins journaled to saidsleeves; shoes secured to said pins and adapted in one position to register with and close the outer ends of said sleeves; and counter weights adjustably secured to said pins so that said shoes may be held in any predetermined position and thereby made to register with said sleeves during a predetermined point in the cycle of rotation of said drum. 

